The invention relates to an elastic spring element.
Special applications require elastically deformable spring elements at high temperatures above 1000xc2x0 C., for example, for applying pressures to hot moving gaskets. Hot elastic gaskets are used, for example, for preventing flow through rudder gaps and hot joints during hypersonic atmospheric flight or during entry into the planet atmosphere. This situation is illustrated in FIG. 1.
The temperature of 1000xc2x0 C. serves therefore as a marker, since above this temperature even high-melting metallic materials begin to creep and their elasticity suffers. At high temperatures their elasticity becomes increasingly poorer because their tensile strength sinks dramatically.
In U.S. Pat. No. 4,441,726 a high-temperature resistant seal is described. It comprises a so-called ceramic rope as the elastic element, the ceramic rope being jacketed in a braid of ceramic fibers.
In U.S. Pat. No. 5,532,239 another high-temperature resistant seal is described which is jacketed in a braid of ceramic fibers.
The invention is therefore addressed to the problem of creating an elastic spring element resistant to high temperature ( greater than 1000xc2x0 C.).
The high-temperature resistant elastic spring element of the present invention made of ceramic fiber material provides an excellent solution of this problem. With the endless fiber-reinforced spring element of the present invention, moving high-temperature gaskets for temperatures above 1000xc2x0 C. can be well achieved. In contrast to all metallic materials, the tensile strength of a ceramic fiber material does not decrease with increasing temperature but even increases slightly. The stiffness of the spring element thus remains even at high temperatures up to at least 1600xc2x0 C. and there is no loss of spring function.
The ceramic fiber material can be made, for example, by laminating technology with the use of a matrix precursor infiltrated with endless fiber prepregs or fabrics. A green body of stable shape created by crosslinking the matrix precursor can be transformed by a subsequent pyrolysis process into the fiber-reinforced ceramic body. The production of the ceramic fiber material can also be performed by the fluid silication process from C/C materials or the chemical vapor infiltration process or a combination of these processes.
The ceramic fiber spring element of the present invention is characterized in that its shaping can be performed independently of the structural composition or stratification of the ceramic fiber material.
The fiber for the spring element of the present invention can consist, for example, of the following materials: reinforcing fibers, endless carbon fibers, or endless ceramic fibers made from oxide or nitride or carbide or silicic ceramic materials or mixed ceramics formed therefrom. The ceramic matrix may consist of carbon or oxide or nitride or boride or carbide or silicic ceramic materials or mixed ceramics formed therefrom.
The elastic element according to the invention can have, for example, a flat shaped, wavy, curved or arcuate or spiral-shaped geometrical form.
The component according to the invention can be laid free with movable ends, e.g., it can be a corrugated spring laid in a groove. It is also possible, likewise, to clamp it tightly on one or more sides or ends, e.g., be a flat spring element which is held at two opposite margins.